The prior art is replete with various types of gripping handles for use with various types of tools or implements. These gripping handles provide a grasping surface for manipulation, allowing an intended user to manually use the tool for its intended function or use.
Grasping of a gripping handle regardless of the type includes four stages. First, opening of the hand, which requires the simultaneous action of the intrinsic muscles of the hand and the long extensor muscles. Second, closing of the fingers to grasp the gripping handle and adapt to the shape of the latter. Third, exertion of a force on the handle, which will vary depending on the weight, surface characteristics, fragility and use of the implement, and its gripping handle. Fourth, release, in which the hand opens to let go of the gripping handle.
In order to provide gripping handles that allow for these four stages to occur satisfactorily while being manufacturable at relatively low costs, most conventional gripping handles have a generally elongated configuration with a substantially constant cross-sectional configuration. Typically, the cross-sectional configuration is disc-shaped, hexagonal or the like.
Such conventional gripping handles are typically grasped using a so-called power grip. With this type of grip, the digits of the user maintain the gripping handle against the palm. The combined effect of joint position brings the hand into line with the forearm. For a power grip to be formed, the fingers are flexed and the wrist is in ulnar deviation and extended. A power grip is typically used when strength or force is the primary consideration.
An example of a power grip is the hook grasp, in which all or the second and third fingers are used as a hook and may involve the interphalangeal joints only or the interphalangeal and metacarpophalangeal joints (the thumb is not involved). Another example is the cylinder grasp, or palmar prehension in which the thumb is used and the entire hand wraps around the entire gripping handle. With the fist grasp, or digital palmar prehension, the hand moves around a narrow gripping handle.
Another type of grip is the so-called precision or prehension grip. Typically, the precision grip is an activity limited mainly to the metacarpophalangeal joints. The palm may or may not be involved, but there is a pulp-to-pulp contact between the thumb and other fingers and the thumb opposes the fingers. This grip is used when accuracy and precision are required.
There are three types of pinch grips. The first is called a three-point chuck, three-fingered, or digital prehension in which palmar pinch, or sub-terminolateral opposition is achieved. With this grip, there is a pulp-to-pulp pinch, and opposition is necessary. An example is holding a pencil. This grip is sometimes called a precision grip with power.
The second pinch grip is the lateral, key, pulp-to-side pinch, lateral prehension, or sub-terminolateral opposition. The thumb and lateral side of the index finger come into contact and may be called a side, lateral or key-pinch. No opposition is needed. An example of this is holding a card or a key.
The third pinch grip is the tip pinch or tip-to-tip prehension, or terminal opposition. With this positioning, the tip of the thumb is brought into opposition with the tip of another finger. This pinch is used for activities requiring fine coordination rather than power.
In other words, the human hand grip typically occurs in either one of two separate planes. Power grips procured in a so-called finger-to-palm plane, which is created between the fingers and the palm of the hand. The precision or prehension grips typically occur in a so-called finger-to-thumb plane created between the index finger and the thumb or the thumb and other fingers.
Although somewhat useful and relatively inexpensive to manufacture, conventional implement gripping handles suffer from numerous drawbacks. One such drawback is that they typically only allow for use of a power-type grip wherein the digits maintain the gripping handle against the palm. Accordingly, they are not well suited for operations requiring accuracy and precision.
In situations requiring both power and precision, such as during various types of culinary operations, precision using conventional handles is typically achieved at the cost of excessive compensation by the hand, wrist and arm of the operator with resultant potential risk for various types of injuries including repetitive-stress types of injuries such as carpal tunnel syndrome or the like.
Another common drawback associated with conventional gripping handles is that they typically do not fit the hand well, allowing only a limited surface area of the hand to contact the gripping handle. A given user is hence required to exert a greater amount of strength to adequately perform a given task. Furthermore, this creates high pressure points on the small portions of the hand contacting the gripping handle which may prove to be uncomfortable and again potentially lead to injuries.
The muscles of the forearm include the flexor digitorum profundus and superficialis, which extend from the elbow into the length of the fingers. When the hand is tightly clasped, for example because of poor fit between the hand and the gripping handle, the muscles of the hand remain in tension and the flexor digitorum is tightly compressed. Furthermore, the hand muscles also compress the radial artery leading to poor arterial circulation to the fingers. This may lead to fatigue over a relatively short operational cycle.
Another drawback associated with conventional gripping handles is that they are poorly designed for certain types of movement such as rotation about the longitudinal axis of the gripping handle and sawing or slicing motion involving translational movement along the longitudinal axis of the gripping handle. Typically, both of these motions are performed more ergonomically with the index and thumb fingers in opposition.
Still furthermore, in situations wherein the use of a given implement may provide some risk of injury if the hand of the intended user either contacts either the implement or its environment, such as when the implement is a knife, most conventional handles suffer from failing to provide adequate safety features. Some kitchen or utility knives include a substantially planer shield adjacent to the forward hand of the handle separating the latter from the blade of the knife and providing the intended user with a pushing surface to facilitate the slicing motion. However, the conventional planer shields typically poorly conform to the configuration of the index finger and, hence, only contact the latter about a relatively small contact surface leading to high pressure points. This relatively high pressure exerted on a small area of the finger may quickly lead to discomfort and/or injury.
Accordingly, there exists a need for an improved implement handle. It is a general object of the present invention to provide such an improved implement handle.